Manchester United are still investigating Donny van de Beek's knee injury he sustained in their Premier League win over Bournemouth.
Van de Beek was forced off in added time of the first half on Tuesday night after his leg buckled under a challenge from Marcos Senesi.
When asked if United knew how long Van de Beek would be sidelined Ten Hag replied: "Not really, we are still doing investigations - it's a knee injury."